Wireless communication systems are being widely deployed in order to provide various kinds of communication services, such as voice or data. The object of the wireless communication systems enables a number of users to perform reliable communication with each other irrespective of their position and mobility.
In general, the wireless communication system is multiple access system capable of supporting communication with multiple users by sharing available radio resources. The radio resources may include, for example, time, frequency, codes, and transmission power. The multiple access system may include, for example, a Time Division Multiple Access (TDMA) system, a Code Division Multiple Access (CDMA) system, a Frequency Division Multiple Access (FDMA) system, an Orthogonal Frequency Division Multiple Access (OFDMA) system, and a Single Carrier Frequency Division Multiple Access (SC-FDMA) system.
SC-FDMA has a low Peak-to-Average Power Ratio (PAPR) owing to a single carrier property while having almost the same complexity as OFDMA. A lower PAPR is advantageous to user equipments in terms of transmission power efficiency. SC-FDMA has been adopted for uplink transmission in 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) (3GPP LTE) as described in the fifth section of 3GPP TS 36.211 V8.1.0 (2007-11) “Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8).”
A base station properly allocates radio resources to each of user equipments in a cell through scheduling. Each of the user equipments may transmit control information or user data to the base station using the radio resources allocated thereto. However, a method of transmitting the control information and a method of transmitting the user may differ. A method of allocating radio resources for the control information and a method of allocating radio resources for the user data may also differ. Accordingly, the radio resources for the control information and the radio resources for the user data may differ. The base station may separately manage the radio resources reserved for the control information and the radio resources reserved for the user data. However, the amount of the radio resources reserved for the control information may be greater than the amount of radio resources actually necessary to transmit the control information, and the amount of the radio resources reserved for the user data may be smaller than the amount of radio resources actually necessary to transmit the user data. Although the radio resources necessary to transmit the user data is insufficient, radio resources, left over after the radio resources reserved for the control information have been used to transmit the control information, are not used to transmit control information or user data. Accordingly, a problem arises because limited radio resources are wasted.
Accordingly, there is a need for a method of transmitting uplink data which is capable of efficiently using limited radio resources.